Method of producing vulcanized rubber



' Patented July 24, 1928.

UNITED STATES WINFIELD soon, or AKRON, 01110, ASSIGNOR are THE RUBBERSERVICE LABORAP PATENT OFFICE.

TORIES GO., OF AKRON, OHIO, A CORPORATION OF OHIO.

METHOD OF PRODUCING VULOANIZED RUBBER.

No Drawing. Original application filed September 9, 1926, Serial No.55,386. Divided and this application filed May 19, 1926.

The present invention is directed to the art of producing vulcanizedrubber.

manufacture of a vulcanized rubber compo- .sition of commercial valueand importance by employing as an accelerator of the vulcanizationprocess, a new type of compound for this purpose as is hereinafter fullyset forth and described.

It is well known in chemistry that the aldehydes and particularly thealiphatic alde-' hydes, react with certain types of organic compoundssuch as the amines and certain amino derivatives and the like to producenew materials known as condensation products. These products arecommonly termed Schif'fs bases. Not only do aldehydes react in thismanner with the primary amino compounds, but they will likewise combineor condense with the secondary amines.

In United States Patent No. 1,586,121, granted May 25, 1926, there wasclalmed a process of preparing vulcanized rubber by employing as avulcanization accelerator, a compound produced by reacting carbon b1-sulfid upon the reaction product of a secondary amine, for examplepiperidine with an aldehyde, such as formaldehyde. The presentapplication is a division of this earlier application referred to and 1sdlrected particularly to the use, as a rubber vulcanization accelerator,of the carbon bisulfid derivative of the reaction product of a secondaryamine, such as piperidine, w1th an unsaturated aldehyde and especiallywith an unsaturated cyclic aldehyde.

One method whereby such a compound may be manufactured is-as follows.secondary amine, for example plperidlne, is reacted with an unsaturatedaldehyde, as furfuraldehyde, preferably in the proportion of twomolecular parts by weight of the amine to one molecular proportion byweight of the aldehyde, and the resulting product is further reactedwith one molecular proportionof carbon bisulfid. The reactions may becarried out with or without the use The.

invention is particularly concerned with the and other aldehydes, suchas aldol, crotonal- Serial No. 110,295.

of tar-like consistenzy. Ina similar manner, the carbon bisulfidderivative of the reaction product of other secondary amines amines suchas di-ethyl-amine, and di-benzylamine and other secondary aliphatic andaromatic amines as well as hydro-collidine and other compoundspresent incommercial pyridine may be used. These various compounds and otherrelated materials may be combined in the proportions stated or in otherproportions if desired, with aldehydes such as formaldehyde, oracetaldehyde and their polymeric forms, or with propionaldehyde,butraldehyde, iso-valeric aldehyde and other aliphatic aldehydes, withacrolein or crotonaldehyde or other unsaturated aldehydes, withoxy-aldehydes such as aldol, or with aromatic aldehydes such asbenzaldehyde, cinnamic aldehyde and the like or with ring compounds suchas furfuraldehyde, and the product reacted with carbon bisulfid in themanner as described.

All the compounds hereinbefore described and particularly the carbonbisulfid derivative of the reaction product of piperidine andfurfuraldehyde prepared in the manner as described, may be used asaccelerating agents of the vulcanization of rubber. The acceler atorsnamed are extremely rapid in theiraction and may be used advantageouslyin so called cold cure cements. The accelerators likewise may be emloyedin heat cured rubber goods as is shown by the following examples. Arubber composition intended for use as a friction stock for a tirecomprises 100 parts of pale crepe rubber, 5 parts of zinc oxide, 2.5parts of sulphur and 0.2 parts of one of my new accelerators of theclassde:

piperidine and furfuraldehyde.

The above composition may be readily pre pared in the usual and wellknown manner by plasticizing or breaking down the rubber on thedifferential mixing mills and then mixing homogeneously therein thefiller, vuleanizing agent and accelerator. The composition is then curedunder pressure in molds for a period of time necessary to ive acommercial vulcanized product depen 'ng on the pressure employed. It hasbeen found, in the case of the mixture described that a commercialvulcanized product is produced after heating for approximately one hourat a temperature of approximately 240 F., which is equivalent to tenpounds gauge pressure per square inch. The vulcanized product is foundto possess a tensile strength of about 2400 pounds per square inch.

Other vulcanization temperatures than than mentioned in the example maybe employed if desired. I have found that the rubber compositiondescribed may for example be completely vulcanized by heating forapproximately fifteen minutes at the temperature given by forty poundsof steam pressure per square inch or after heating for approximatelythree hours at the temperature given by a steam pressure ofapproximately five pounds per square inch. It is apparent then that avulcanized rubber of high quality results from theuse of my new type ofaccelerators under varying curing conditions.

Other rubber com ositions may likewise be prepared by emp oying any ofmy new type of accelerators. Thus, a semi-translucent stock that may beused in the manufacture of druggist sundries, such as hot water bottles,nipples, etc, may be prepared from a mixture comprisin 100 parts of palecrepe rubber, 0.5 parts of zinc oxide, 1.5 parts of sulfur and 0.5 partsof one of my new accelerators of the type set forth herein. This mixturewill yield a commercial product when vulcanized for approximately 25minutes under the pressure of approximately 20 pounds of steam persquare inch.

The accelerators as herein described may likewise be employed in themanufacture of a hard rubber. Thus, for example, 100 parts of pale creperubber, 150 parts of zinc sulfid, 5 parts of zinc oxide, parts of sulfurand 2 parts of any of my preferred class of accelerators may be mixedtogether in the usual manner and cured for a period of approximately onehour and 45 minutes at a pressure of 40 pounds of steam per square inch.A bright red hard rubber of high quality may be obtained byincorporating into the above composition substantially 20 parts of asuitable colorin material, such as a naphthalamine color.

ther dyes may, of course, be used if desired.

The accelerators herein described are sufli- .ciently rapid in theiraction to produce a not limited by any theory set forth in explanationof the facts involved nor are the examples given to be considered aslimita tive of my invention. -For example, it is within the scope of myinvention, when my preferred compounds are used in the acceleration of aso called cold cure or rubber cement, that instead of using theaccelerators their accelerating powers as formed. Other 1 means of usingthe accelerators herein described are apparent to those skilled in theart. It is, of course, possible to use other types of rubber than thatmentioned in the examples while other fillers may be employed togetherwith or in place of zinc oxide.

My invent-ion is, then to be regarded as defined solely by the claimshereinafter set forth wherein I intend to claim all novelt permissiblein view of the prior art. i

What I claim is:

1. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction prodnot of a secondary amine and anunsaturated aldehyde.

2. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction product of a secondary amine and a cyclicaldehyde.

3. The process of manufacturing vulcan- 5. The process of manufacturingvulcanized rubber which comprises heating rubber and sulphur in thepresence of the carbon bisulfid derivative of the reaction product of asecondary amine and with furfuralde- 8. The process of manufacturingvulcan-' ized rubber which comprises heating rubber and sulphur in thepresence of the carbon bisulfid derivative of the reaction product of acompletely hydrogenated cyclic imino iOIlPOUDd and an unsaturated cyclicaldey e. I

9. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction product of a completely hydrogenated cyclicimino compound and an aldehyde containing more than two carbon atoms.

10. The'process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction product of a completely hydrogenated cyclicimino compound and furfuraldehyde.

11. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the-carbon bisulfidderivative of the reaction product of piperidine and an unsaturatedaldehyde.

12. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction product of piperidine and a cyclic-aldehyde.

13. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction product of piperidine and an unsaturatedcyclic aldeh de.

14. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction product of piperidine'and an aldehydecontalning more than two carbon atoms.

15. The process of manufacturing vulcanized rubber which comprisesheating rubber and sulphur in the presence of the carbon bisulfidderivative of the reaction product of piperidine and furfuraldehyde.

16. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a secondary .amine and an unsaturated aldehyde.

17. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a secondary amine and a cyclic aldehyde.

18. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a secondary amine and an unsaturated cyclicaldehyde.

19. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a secondary amine and an aldehyde containingmore than two carbon atoms.

20. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a secondary amine and furfuraldehyde.

21. The vulcanized rubber product ob-. tained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a completely hydrogenated cyclieimino compoundand an unsaturated aldehyde.

22. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a completely hydrogenated cyclic imino compoundand a cyclic aldehyde.

4 23. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a completely hydrogenated cyclic imino compoundand an unsaturated cyclic aldehyde.

24:. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofthe reaction product of a completely hydrogenated cyclic imino compoundand furfuraldehyde.

25. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofpiperidine and an unsaturated aldehyde.

26. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid deigiivative ofpiperidine and a cyclic aldeh e.

27. The vulcanized rubber product obtained by heating rubber and avulcanizing agent in the presence of the carbon bisulfid derivative ofpiperidine and an unsaturated tained by heating rubber and a vulcanizingcyclic aldehyde. agent in the presence of the carbon bisulfid 10 28. Thevulcanized rubber product obderivative of piperidine andfurfuraldetained by heating rubber and a vulcanizing hyde. 5 agent inthe presence of the carbon bisulfid Signed at Akron, in the county ofSumderivative of piperidine and an aldehyde mit, and State of Ohio, this14th day of containing more than two carbon atoms. May, A. D. 1926.

29. The vulcanized rubber product ob- WINFIELD SCOTT.

